Boxed copies fly off the shelves - but what of the elusive Steam figures?

Valve's critically acclaimed first-person shooter Half-Life 2 has clocked up almost 1.7 million retail sales since its launch less than two months ago, according to the latest information from publisher Vivendi Universal Games.

The game doesn't appear to have seen its fortunes dented by the long series of delays which afflicted its development, which saw the release date being pushed back by more than a year in a number of highly publicised slips.

VU Games notes that outside of the United States, sales of the game have been particularly strong in European territories such as Germany, the UK, France, Italy, Spain and Scandinavia.

Presumably based on the long-term success of the original Half-Life - which remained a strong performer at retail several years after its original release - VUG is hoping that the title will continue to sell well in the coming months, and describes it as "set to become one of the biggest hits of 2005".

However, there's no mention of the Steam online distribution system, which Valve used to deliver copies of the game directly to the home PCs of consumers who bought it over the Internet.

Valve and Vivendi are still engaged in a legal spat over the service, and sales figures from Steam are not included in the 1.7 million figure. Valve itself has remained silent on the question of sales over Steam - but developers, publishers and retailers alike will undoubtedly be keen to find out just how well the brave experiment in online distribution performed commercially for one of the most anticipated PC titles of all time.